1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method for producing the same, and an electrophotographic apparatus and a process cartridge having an electrophotographic photosensitive member.
2. Description of the Related Art
For the purpose of improving the durability of an electrophotographic photosensitive member containing an organic photoconductive substance, technologies have been explored to improve materials, characteristics, and other features of the surface of an electrophotographic photosensitive member.
Japanese Patent Laid-Open No. 2008-262232 describes that the surface layer of an electrophotographic photosensitive member contains a polymer of a hole transporting substance having a chain-polymerizable functional group and also contains a lubricant so that the wear resistance and potential characteristics during repeated use should be improved.
Furthermore, for the purpose of improving cleaning performance for toner that remains on an electrophotographic photosensitive member after image transfer, technologies have been explored in which the surface layer of a photosensitive member contains a lubricating substance. For example, Japanese Patent Laid-Open No. 62-75462 discloses a technology in which the surface of an electrophotographic photosensitive member contains a certain silicone-based comb-shaped graft polymer so that cleaning performance and the lubricity of the surface of the electrophotographic photosensitive member should be improved.
In recent years, it has been demanded that electrophotographic apparatus use an electrophotographic photosensitive member with improved wear resistance and the quality of images produced therewith be improved. In particular, color electrophotographic apparatus has problems such as streak-like image defects, which occur due to a reduced lubricity of an electrophotographic photosensitive member during repeated use, and image smearing, which occurs due to, conversely, too high a lubricity of an electrophotographic photosensitive member. It is therefore in demand to reduce streak-like image defects while reducing image smearing. Research conducted by the inventors has found that the electrophotographic photosensitive members described in Japanese Patent Laid-Open No. 2008-262232 and Japanese Patent Laid-Open No. 62-75462 have room for improvement because with these technologies, it can in some cases be impossible to sufficiently reduce streak-like image defects while sufficiently reducing image smearing.
Image smearing is a phenomenon manifested as a blurred output image that occurs secondary to a blurred electrostatic latent image. Researchers speculate that this is because a reaction product formed through the reaction between moisture existing on the surface of an electrophotographic photosensitive member or in the air and a corona product formed through charging alters the materials constituting the surface layer of the photosensitive member.
To reduce image smearing, a method has been used in which a drum heater is placed to increase the surface temperature of an electrophotographic photosensitive member and thereby to evaporate moisture, a factor in causing image smearing. As for streak-like image defects, a method may occasionally be used in which conditions such as the contact pressure that occurs when a cleaning blade comes into contact with an electrophotographic photosensitive member are optimized to reduce image defects. However, an electrophotographic photosensitive member that allows both streak-like image defects and image smearing to be reduced without using these methods is in demand from the viewpoints of saving the energy consumed by electrophotographic apparatus and cleaning performance for residual toner.